Peter Cullen Talks Optimus Prime Voicing of Transformers 4 Age of Extinction Character - New Image

Peter Cullen has been voicing the heroic Autobot leader Optimus Prime for 30 years, from the 1980s "Transformers" cartoons to the new movie "Transformers: Age of Extinction." (Photo: ILM / Paramount Pictures)

The fan-favorite robot: Optimus Prime in Transformers: Age of Extinction.

Optimus Prime has undergone quite a few vehicular makeovers in the past 30 years of Transformers projects, yet his earnest and heroic voice has never wavered, thanks to Peter Cullen.

For the big-budget Transformers: Age of Extinction, the actor once again reprises the role he's been playing since the 1980s Transformers cartoon. Now Prime and his Autobots have a new human ally (Mark Wahlberg) but they are in conflict with the evil Decepticons as well as the U.S. government.

"He is exactly who he was from the very original concept," Cullen says of Prime. "I've always felt a hero should have the qualities that are inspiring and helpful and fatherly and at the same time (be) courageous. I don't see those character traits changing at all."

Transformers is more than a lifetime gig as a transforming big rig for Cullen. It's also a family affair: His son Clay is a stuntman on Age of Extinction, and Cullen's brother Larry, a Marine who served in the Vietnam War and died in 2011, continues to be the inspirational foundation for Optimus' steady and strong tone.

"Though Larry's gone," Peter Cullen says, "he lives on in my mind as Optimus Prime because he was my hero."